The present invention is related to occupant detection systems, and in particular, to occupant detection systems that can readily classify an object in a seating area, such as to control an air bag or to generate a warning.
Air bag devices ease the shock that a passenger experiences during an automobile collision. Air bags are installed in front of the driver's and passenger's seats. Air bags may be installed in other locations, such as to the side of a forward facing passenger.
When a rear facing infant seat (hereafter RFIS) is located on the front passenger seat, it is desirable for the passenger-side air bag not to deploy. It may also be desirable for the passenger-side air bag not to deploy for a forward facing child seat (hereafter “FFCS”) or child. Likewise, deployment may be limited for side impact airbags based on whether a child or short person is leaning towards the air bag. It may also be desired to avoid deployment where only inanimate objects are in the seating area to save replacement costs.
Passenger detection sensor types have been proposed for detecting a RFCS, an FFCS or children. Systems using electric fields to detect characteristics of a load in a seat are disclosed in U.S. Pat. Nos. 5,948,031, 6,329,913, and 6,329,914. Other systems using capacitive sensing, such as systems to detect a change in phase or frequency due to the presence of a passenger, have also been proposed. Both types of systems rely on transmission and reception from one or more antenna or electrodes.